Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!uunet!ogicse!uidaho!wallaby.mrc.uidaho.edu!smith
From: smith@wallaby.mrc.uidaho.edu
Newsgroups: comp.sys.hp
Subject: Re: Using an 8mm Exabyte Drive on a 400s
Message-ID: <1991May02.212120.12618@groucho>
Date: 2 May 91 21:21:20 GMT
References: <1991Apr30.161540.10889@serval.net.wsu.edu>
Sender: @groucho
Distribution: usa
Organization: University of Idaho
Lines: 39
Nntp-Posting-Host: wallaby.mrc.uidaho.edu

In article <1991Apr30.161540.10889@serval.net.wsu.edu> eric@yoda.eecs.wsu.edu (Eric Schneider) writes:
>Hi -
>
>	I'm trying to get our 8mm Exabyte drive to function optimally on
>a HP/Apollo 400s.  The problem is that using rdump(1) seems to give a lot
>less capacity than the rated values for this drive.  Can somebody give me
>a clue as to why this is?  The exabyte writes 1K blocks on the tape and
>puts an 8K gap when the buffer runs out of data.  Is /etc/rmt somehow
>responsible for writing 512 byte blocks to this device?  I'd be very
>interested in hearing from people who have seen near-capacity storage
>on this type of drive using rdump.

  I believe that dump is responsible for the small block sizes.  The drive
is most efficient (both in speed and space) when block sizes which are
multiples of 8K are used.

>
>	I'd also entertain suggestions for alternative backup programs.
>Rdump provides a very straightforware means for restoring files (as in
>restore ivf) and that is why I would like to use it.

  Try ftio.  That seems to be the most efficient.   It allows you to set
the block size to just about anything.

                                          __        
                                         |  |
-----------------------------            |  |
William Smith                            |. |  
Microelectronics Research Center         \  | 
University of Idaho                      /   \ 
Moscow, ID  83843                        |    \    
(208)885-6500                            |     \  
                                         |      ---|          
E-mail:   wsmith@groucho.mrc.uidaho.edu  |         |   
----------------------------             |         |
                                         |----------